FR2768809A1 - LARGE CALIBER LONG RANGE FIELD ARTILLERY PROJECTILE - Google Patents

Abstract

The technical sector of the invention is that of ammunition, in particular of large caliber campaign. The invention relates to an artillery projectile (1), intended to be fired from a tube of large caliber cannon , comprising a body (2) equipped at the rear part (5) with a deployable stabilizing stabilizer (12), characterized in that the body (2) is sub-calibrated and carries at least one ejectable guide shoe (6) equipped with a slip belt (10) intended to reduce the speed of rotation of the projectile.

Description

l The technical field of the invention is that of projectiles, in

  especially large-caliber long-range field artillery projectiles. Increasing the range of artillery projectiles has always been sought. Thus, a base-bleed has been installed on the rear of the ballistic trajectory projectiles which is intended to reduce the base drag by emitting gases developed by the combustion of a composition such as a propellant. The base-bleed increases the range of the projectiles only of the order of 5 to 10% and generates dispersions detrimental to the precision of the shooting. It has also been proposed, to increase the accuracy of the shot, to make a trajectory correction or a terminal guidance. But ballistic trajectory projectiles being gyrostabilized, it is very difficult to

  perform correct trajectory correction or terminal guidance. In addition, only the precision is improved, the range being always relatively small.

  Patent W08100908 proposes an artillery projectile comprising a base-bleed provided with a belt, guide fins and a stabilization stabilizer. This projectile is gyrostabilized on a part of its trajectory during which the base-bleed is operational, then the base-bleed25 is ejected, which allows the deployment of the stabilization stabilizer which slows the rotation of the projectile. The projectile thus finds itself on a trajectory stabilized by the tail. Then a terminal guidance can be carried out using the guide fins. Such a concept has several drawbacks. First, the transition from the gyrostabilized trajectory to the stabilized stabilization by empennage generates many constraints. Indeed, the tail receives very high mechanical stresses during its deployment which can cause a loss of stability of the projectile and / or significant dispersions. Then the range of such a projectile, as has been explained before, is relatively small. It is the object of the invention to propose a projectile which is simple, inexpensive, with a large firing range. Thus, the subject of the invention is an artillery projectile, intended to be fired from a large caliber cannon tube, comprising a body fitted at the rear with a deployable stabilizing stabilizer, characterized in that the body is under-calibrated and carries at least one ejectable guide shoe equipped with a slip belt intended to reduce the speed of rotation of the projectile. 10 According to a particular embodiment, the guide shoe is positioned at a rear part of the

  body of the projectile while maintaining the deployable stabilization stabilizer, the deployment of the latter taking place during the ejection of the rear shoe at the outlet of the tube.

  Advantageously, it comprises a second guide shoe positioned at a front part of the projectile and

ejectable at the outlet of the tube.

  The front shoe consists of at least two segments linked to the body by a temporary connection means consisting of at least one shearable pin, the shearing being caused by a relative retraction of the shoe relative to the body of the projectile during acceleration longitudinal of the projectile in the barrel tube.25 Advantageously, the front shoe has an internal profile complementary to an external profile of the front part

  of the projectile and there is an axial clearance between the internal profile of the sabot and the external profile of the front of the projectile so as to allow the relative recoil of the sabot relative to the body of the projectile during the longitudinal acceleration of the latter in the barrel tube.

  According to one embodiment, the projectile comprises, in the front part, deployable control surfaces.

  Advantageously, the rear shoe comprises a thrust piece receiving the slip belt and a tubular piece covering the rear part of the body of the projectile while

  maintaining the stabilization stabilizer in its folded position.

  According to a particular embodiment, the projectile comprises a rear propellant.

  According to a first alternative embodiment, the rear shoe is ejected at the outlet of the barrel tube by the pressure generated by the propellant. According to a second alternative embodiment, the rear shoe is ejected by a pyrotechnic charge placed between the thrust piece of the rear shoe and the rear part of the body of the projectile. 10 Preferably, the tubular part of the rear shoe has longitudinal weakening zones, intended

  to break during the ejection of the hoof in order to increase the aerodynamic drag thereof.

  The invention will be better understood on reading the

  description of a particular embodiment, made with reference to the accompanying drawings in which:

  - Figure 1 shows an external view of an artillery projectile according to the invention.

  - Figure 2 shows the artillery projectile according to the invention with the front and rear sabots ejected.

  - Figure 3 shows a partial section of the front part of the projectile according to the invention.

  - Figure 4 shows a partial section of the

  front part of the projectile after separation of the hoof and the body.

  Referring to FIG. 1, a large-caliber field artillery projectile 1, according to the invention, consists of a body 2 carrying in the front part 3 a first ejectable sabot 4 and in the rear part 5 a second sabot

ejectable 6.

  The front shoe 4 is composed of several segments 7, here three in number, linked to the projectile body 2 by

  radial pins 8. Each segment 7 can be produced from an organic material, for example of the loaded thermoplastic type.

  The rear shoe 6 comprises on the one hand a thrust piece 9 carrying on its periphery a slip belt, and on the other hand a tubular piece 11 covering the rear part 5 of the body of the projectile. The tubular part 11 is made integral with the thrust part 9, for example by gluing. The thrust piece 9, made of steel, is intended to receive the propellant gases during the gun phase. The tubular part 11 is made of thermoplastic. The front 4 and rear 6 shoes are intended to guide the projectile inside a barrel tube

of a weapon not shown.

  This type of structure composed of a front guide and a rear guide which are relatively distant from each other is particularly suitable for a projectile of great length.15 The body 2 is therefore undersized relative to the diameter internal of the barrel of the barrel tube, which makes it possible to increase the initial speed while decreasing the aerodynamic drag coefficient of the projectile and therefore to increase its range.20 The body 2 is intended to transport a payload not shown, which may be submunitions

  intended to be dropped above a target. To stabilize a projectile on its trajectory, we use either the gyroscopic effect or a tail.

  Field artillery projectiles are usually fired from large barrel tubes

  caliber, of the 155 mm type, having internal stripes intended to impart to them a high speed of rotation in order to stabilize them on the trajectory. These projectiles are said to be gyrostabilized.

  The artillery projectile according to the invention is intended to carry a payload of large volume, by

  example several submunitions. This carrying therefore requires a long length of projectile which prohibits stabilization of the projectile by gyroscopic effect.

  Stabilization of the projectile 1 according to the invention is ensured by a tail 12 (see fig 2) placed in the rear part 5 of the body 2 and which deploys at the outlet of the barrel tube. The slip belt 10, of the type described in patent FR2606869, is intended to take the scratches from the barrel tube and to slip on the thrust piece 9 in order to reduce the speed of rotation of the projectile. Thus at the exit of the barrel tube, the projectile is subjected only to a low rolling speed of the order of 10 revolutions / s. This low rolling speed of the projectile advantageously allows the deployment of the tail at the outlet of the tube under good conditions, under low stresses which do not disturb the stability of the projectile. The stabilization stabilizer 12 consists of four flat blades made of very high limit steel

  elastic. Each blade is articulated at its root and lockable in the deployed position.

  The blades of the tail unit 12, shown in the deployed position in FIG. 2, were initially wound on the outside of the rear part 5 of the body 2 of the projectile20 and held in position by the tubular part 11 of the shoe 6. The attachment of the rear shoe 6 and body 2 is provided by the support of the tail fins 12 on the

  internal surface of the tubular part 11 of the shoe 6. The blades are kept constrained in the wound position by the shoe 6.

  The body 2 has at its rear part 5 an additional propellant 13 intended to increase the range of the projectile.

  The additional propellant 13 is constituted, in a conventional manner, of a body of high-strength steel comprising an ejection nozzle 14 for the propellant gases. It comprises a propellant charge consisting of a solid propellant block of the double base type. At the outlet of the weapon barrel, the additional propellant 13 is ignited, for example by borrowing propellant gases through an axial opening provided in the powdered plate 9. The high pressure gases produced by the combustion of the charge propellant are ejected by the ejection nozzle 14 by generating an axial thrust. This generation of propellant gases ensures the separation and then the ejection, behind the projectile, of the rear shoe 6. In FIG. 2, the segments 7 of the front shoe 4 are in a position separated from the body 2. The ejection of the front shoe is effective at the outlet of the tube, after a rupture of the pins 8 as will be explained later, thanks to the aerodynamic forces which are exerted on the front of the shoe and which allow the spacing of the segments 7.10 The front part 3 of the body 2 of the projectile comprises deployable control surfaces 15, here four in number. These control surfaces are deployable through slots 17 made on the body 2. They are deployed on a trajectory at a given instant as will be explained more

  far. They are intended to guide the projectile.

  The front part 3 also includes a ballistic warhead 16 containing a set of guiding and piloting equipment (not shown), in particular roll, yaw, pitch gyrometers, a GPS locator with its antennas, an actuator module control surfaces with reducing servomotors, as well as an energy source and an order processor. Figure 3 shows a partial section of the part

front 3 of projectile 1.

  The front part 3 of the projectile 1 carries the shoe 4 composed of the three segments 7 made integral with the body 2 by radial pins 8. The segments 7 of the shoe have an internal profile 17 complementary to the external profile 18 of the warhead 16. When the shoe 4 is linked to the body 2 by the pins 8, as shown in FIG. 3, an axial clearance 19 persists between the two profiles 17 and 18, the segments 7 of the shoe being in the advanced position relative to the body 2.35 When putting with fire from the propellant charge of the ammunition inside the barrel tube, the pressure generated by the combustion gases of the propellant charge is exerted on the thrust plate 9 of the rear shoe 6 and pushes the projectile 1 to the inside the barrel tube. The frictional forces between the front shoe 4 and the scratches of the barrel of the weapon counteract the significant longitudinal acceleration of the projectile, and a shearing force is therefore created at the pins 8, causing them to break. The segments 7 of the shoe 4 separate from the body 2 and the front shoe then moves back relative to the body until the profile 17 of the shoe stops on the external profile 18 of the warhead 16 and disappearance of the game 19.10 The figure 4 shows this phase at the end of the relative retreat of the segments 7 of the front shoe relative to the body 2, when the two profiles 17 and 18 are in contact. In this configuration, the segments 7 of the shoe 4 are separated from the body 2 of the projectile, the pins being broken. At the end of the barrel tube, the aerodynamic pressure which is exerted on a front conical surface 20 of the shoe 4 causes the segments 7 to open and then to be ejected. The different stages of operation of the artillery projectile according to the invention are the following: - Internal ballistics phase in the barrel tube: * firing of the propellant charge, * rupture of the connecting pins 8,

  * relative recoil of the segments 7 of the front shoe 4 relative to the body 2.

  - Ballistic flight phase, from the exit of the barrel tube: * ejection of the segments 7 of the front shoe 4, * ignition of the additional thruster 13, * ejection of the rear shoe 6,

  * opening of the stabilization stabilizer 12.

  - Pilot flight phase, substantially from the peak of the trajectory: * opening of the control surfaces 15 controlled by the servomotors,

  * guidance-piloting of the projectile towards the target.

  The control surfaces 15 are advantageously only opened after the apogee in order to reduce the aerodynamic drag and to ensure sufficient stability in ballistic flight. Thus, the projectile according to the invention, being of the sub-calibrated type and equipped with an additional propellant, allows the carrying of a large payload, of the order of 30 kg at a very large firing distance. around 60 to 80 km.

  Of course, without departing from the scope of the invention, other variants can be envisaged.

  For example in the case where the additional thruster would only be ignited during the trajectory, for example by an electrical initiation, the rear shoe can be ejected by a pyrotechnic charge 21 placed between the thruster 13 and the thrust plate 9 of the rear shoe 6 and on as soon as it leaves the barrel tube (see Figure 5). This pyrotechnic charge 21 could be ignited by means of a propellant gas loan, for example through a

  axial opening 22 arranged in the thrust plate 9, a pyrotechnic delay 23 ensuring the ejection of the rear shoe 6 after the exit from the barrel of the weapon.

  A pyrotechnic charge of this type can, of course, complete the means for ejecting the rear shoe 6 by the propellant 13 described in FIG. 2. In fact, the rise in pressure of the propellant is not immediate, rapid separation of the shoe by a pyrotechnic charge would have the advantage of releasing the stabilization stabilizer as soon as it leaves the barrel tube, thereby improving the stabilization of the projectile. A weakening of the tubular part 11, by longitudinal precuts 24 of its wall (shown in FIG. 5), can also be envisaged in order to improve its aerodynamic braking as soon as it is ejected at the outlet from the barrel tube. Thus the pressure generated by the pyrotechnic ejection charge 21 and / or the propellant 13 will cause the tubular part 11 to be cut at the weakening zones 24. The tubular part 11 will then open in the form of petals, thereby increasing its aerodynamic braking.

Claims (6)

  1 - Artillery projectile (1), intended to be fired from a large caliber cannon tube, comprising a body (2) fitted at the rear (5) with a deployable stabilization stabilizer (12), characterized in that the body   is sub-calibrated and carries at least one ejectable guide shoe (6) equipped with a slip belt (10) intended to reduce the speed of rotation of the projectile.   2 - Projectile according to claim 1, characterized in that the guide shoe (6) is positioned at a   rear part (5) of the projectile body and in that it maintains the deployable stabilization stabilizer (12), the deployment of the latter taking place during the ejection of the rear shoe at the outlet of the tube.   3 - Projectile according to any one of the claims   1 or 2, characterized in that it comprises a second guide shoe (4) positioned at the level of a front part (3) of the projectile and ejectable at the outlet of the tube. 20 4 - Projectile according to claim 3, characterized in that the front shoe (4) consists of at least two segments (7) linked to the body by a temporary connection means 5 - Projectile according to claim 4, characterized in that the temporary connection means consists of at minus a shear pin (8), the shear being caused by a relative recoil of the shoe (4) relative to the body (2) of the projectile during the longitudinal acceleration of the projectile in the barrel tube. 6 - Projectile according to claim 5, characterized in that the front shoe (4) has an internal profile (17) complementary to an external profile (18) of the front part of the   projectile, and that there is an axial clearance (19) between the internal profile of the sabot and the external profile of the front of the projectile so as to allow the relative retraction of the sabot relative to the body of the projectile during longitudinal acceleration of the latter in the barrel tube.   7 - Projectile according to any one of claims   1 to 6, characterized in that it comprises in the front part (3) deployable control surfaces (15).   8 - Projectile according to claim 2, characterized in that the rear shoe (6) comprises a thrust piece (9) receiving the slip belt (10) and a tubular piece (11) covering the rear part of the body of the projectile while maintaining the stabilization stabilizer (12) in its folded position.   9 - Projectile according to any one of claims   1 to 8, characterized in that it comprises a rear thruster (13). 10 Projectile according to claim 9, characterized in that the rear shoe (6) is ejected at the outlet of the barrel tube by the pressure generated by the propellant (13). 11 - Projectile according to claim 8, characterized in that the rear shoe (6) is ejected by a pyrotechnic charge (21) placed between the thrust piece (9) of the rear shoe (6) and the rear part of the body of the projectile . 12 - Projectile according to claim 8, characterized in that the tubular part (11) of the rear shoe (6) has longitudinal weakening zones (24), intended to break during the ejection of the shoe in order to increase the   aerodynamic drag of it.